Patterns of inversion polymorphism in three species of the Drosophila melanogaster species group

In Drosophila, chromosomal polymorphism due to paracentric inversions is very common and constitutes an adaptive character. The degree of chromosomal variability varies in different species and also in different populations of the same species. Chromosomal polymorphism in Indian natural populations of three species, D. melaonogaster, D. ananassae and D. bipectinata which belong to the melanogaster species group has been studied and the quantitative data on frequency of inversions have been reported. Behaviour of chromosome inversions has also been studied in laboratory conditions. The present review summarises the work done on inversion polymorphism in Indian populations of three species which clearly demonstrates that these three species vary in their patterns of inversion polymorphism and have evolved different mechanisms for adjustment to their environments although they belong to the same species group.